Duke, actually most people erroneously assume that Mobil1 as a brand is bad for all Subaru's. Someone did one random uoa here on an n/a Impreza and has declared that Mobil1 sucks in n/a Subaru's because it sheared to a 20 grade.

And in most oil threads on the BRZ and FR-S forums, many people are posting that they hear that Mobil1 is bad for boxers.